The majority of present day integrated circuits are implemented by using a plurality of interconnected field effect transistors (FETs), also called metal oxide semiconductor field effect transistors (MOSFETs), or simply MOS transistors. A MOS transistor includes a gate electrode as a control electrode and spaced apart source and drain regions between which a current can flow. A control voltage applied to the gate electrode controls the flow of current through a channel between the source and drain regions.
In such modern integrated circuits, the reliability and performance of certain circuit portions may be determined by material characteristics and process techniques for forming highly sophisticated circuit elements, while other circuit portions may used to form less critical devices, which may thus provide a different behavior over the lifetime compared to critical circuit portions. Consequently, the combination of the various circuit portions in a single semiconductor device may result in a significantly different behavior of the device with respect to performance and reliability, wherein the variations of the overall manufacturing process flow may also contribute to a further discrepancy between the various circuit portions.
For these reasons, in complex integrated circuits, additional mechanisms may be implemented so as to allow the circuit itself to adapt the performance of certain circuit portions to comply with the performance of other circuit portions. This adaptation may be necessary upon completing the manufacturing process and/or during use of the semiconductor device, for instance when certain critical circuit portions may no longer comply with corresponding performance criteria, thereby requiring an adaptation of certain circuit portions, such as re-adjusting an internal voltage supply, resetting overall circuit speed, and the like.
For this purpose, so-called electronic fuses, or “e-fuses,” may be provided in the semiconductor devices. E-fuses represent electronic switches that are activated once in order to provide a desired circuit adaptation. Hence, the electronic fuses are considered as having a high impedance state, which typically also represent a “programmed” state, and have a low impedance state, typically representing a non-programmed state of the electronic fuse. Because these electronic fuses are actuated once over the lifetime of the semiconductor device under consideration, a corresponding programming activity has to ensure that a desired programmed state of the electronic fuse is reliably generated in order to provide well-defined conditions for the further operational lifetime of the device. Activation of the e-fuse typically involves passing a relatively high current through the fuse which, given the relatively high resistance of the structure, causes the e-fuse to at least partially physically and structurally disintegrate, or as is commonly referenced in the literature, to “blow.”
Current e-fuses are executed in one wiring level only. To obtain sufficient resistance in order to reliably ensure the appropriate programming state, the e-fuse lengths are relatively long, which undesirably results in a large area “foot print” on the integrated circuit. Furthermore, in order to have a sufficiently-high resistance, minimum e-fuse widths are used, which in some prior art methods may be stabilized by lithographic but electrically inactive support lines. These support lines also consume extra foot print area without providing any functional purpose with regard to the e-fuse.
Accordingly, it is desirable to provide improved integrated circuits that include e-fuses with a reduced footprint area on the integrated circuit. It further is desirable to provide such integrated circuits that avoid the need for electrically inactive support lines. Still further, it is desirable to provide such integrated circuits having e-fuses with a high degree of reliability. Furthermore, other desirable features and characteristics of the present disclosure will become apparent from the subsequent detailed description and the appended claims, taken in conjunction with the accompanying drawings and the foregoing technical field and background.